The influence factors of discrete degree of lithium-ion batteries and optimization
Lithium battery in the process of group, due to the nuances of lithium batteries itself constitute materials and the different levels of group technology, can make the lithium batteries appeared in the process of use and placement function inconsistent phenomenon, that is the discrete phenomena of lithium-ion batteries, describe the quantitative indicators of the discrete phenomenon is discrete, it is composed of a function of several parameters obtained, mainly include: of the change of the degree of discrete numerical resistance, temperature, voltage, capacity, etc. 1, battery internal resistance, especially the polarization resistance, makes the individual cells in the process of charging and discharging voltage change drastically, which leads to the dramatic changes of the whole battery pack; 2, monomer battery voltage does not agree, will affect the battery load capacity, the overall lowering the energy of battery pack release; 3, due to the heat release and absorption of heat batteries work process, the battery temperature will continue to change, when overheating, will lead to performance degradation and potential safety hazard, it has been proved that happened in recent years, the electric car operation and testing of all because of a warm fire heat of the fire protection does not reach the designated position caused by battery, battery types not only have a manganese acid lithium, lithium iron phosphate battery, too; 4, capacity is one of the most serious factors in discrete, capacity of inconsistency caused by two main aspects of the performance problems, one is the part of the battery will be charge discharge state, lead to unsafe factors such as combustion, explosion, the second is the low capacity of monomer battery for finish work early and affect the whole battery pack in the rest of the monomer battery energy cannot be fully released, causing the whole the life of the battery pack. Lithium batteries in order to reduce the negative effect of discrete degree, maximum limit satisfy the requirement of uniformity of the battery pack, need to make and use from the following angles to improve. 1, the production process, the lithium battery design ensure that accord with the requirement of large-scale mechanization production, look for ways to control the quality of the products process, ensure the monomer battery in the uniformity of material and internal structure. 2, in use, the first thing to optimize separation matching technology, makes the lithium-ion battery pack in the early use of consistency to meet; Followed by weakening the battery internal temperature imbalance, current density uniform as far as possible, reduce the battery contact resistance of the connection. 3, testing the battery surface temperature and velocity, choose the rational and scientific ventilation structure, make the whole uniform surface temperature of the battery, ensure the battery when using each battery at the same temperature environment. Poor battery consistency is made more difficult to grasp the process in the process of the battery pack, the current control methods are not perfect, but for the lithium battery into discrete degree of understanding, to improve the consistency of lithium-ion batteries is necessary, is also the foundation of doing this thing.